131 research outputs found
Search for the active ingredients from a 2-aminothiazole DMSO stock solution with antimalarial activity
Chemical decomposition of DMSO stock solutions is a common incident that can mislead biological screening campaigns. Here, we share our case study of 2-aminothiazole 1, originating from an antimalarial class that undergoes chemical decomposition in DMSO at room temperature. As previously measured biological activities observed against Plasmodium falciparum NF54 and for the target enzyme Pf IspE were not reproducible for a fresh batch, we tackled the challenge to understand where the activity originated from. Solvent- and temperature-dependent studies using HRMS and NMR spectroscopy to monitor the decomposition led to the isolation and in vitro evaluation of several fractions against Pf IspE. After four days of decomposition, we successfully isolated the oxygenated and dimerised compounds using SFC purification and correlated the observed activities to them. Due to the unstable nature of the two isolates, it is likely that they undergo further decomposition contributing to the overall instability of the compound
Targeting the IspD Enzyme in the MEP Pathway: Identification of a Novel Fragment Class
The enzymes of the 2-C-methylerythritol-d-erythritol 4-phosphate (MEP) pathway (MEP pathway or non-mevalonate pathway) are responsible for the synthesis of universal precursors of the large and structurally diverse family of isoprenoids. This pathway is absent in humans, but present in many pathogenic organisms and plants, making it an attractive source of drug targets. Here, we present a high-throughput screening approach that led to the discovery of a novel fragment hit active against the third enzyme of the MEP pathway, PfIspD. A systematic SAR investigation afforded a novel chemical structure with a balanced activity–stability profile (16). Using a homology model of PfIspD, we proposed a putative binding mode for our newly identified inhibitors that sets the stage for structure-guided optimization
Targeting the IspD enzyme in the MEP pathway: identification of a novel fragment class
Enzymes of the 2-C-methylerythritol-d-erythritol 4-phosphate 2C-methyl-D-erythritol 4-phosphate (MEP) pathway (MEP pathway or non-mevalonate pathway) are responsible for the synthesis of universal precursors of the huge large and structurally diverse family of isoprenoids. This pathway is absent in humans, but present in many pathogenic organisms and plants, making it an attractive source of drug targets. Here, we present a high-throughput screening approach that led to the discovery of a novel fragment hit active against the third enzyme of the MEP pathway, PfIspD. A systematic SAR investigation afforded a novel chemical structure with a balanced activity-stability profile (16). Using a homology model of PfIspD, we proposed a putative binding mode for our newly identified inhibitors that sets the stage for structure-guided optimization
Search for the Active Ingredients from a 2-Aminothiazole DMSO Stock Solution with Antimalarial Activity
Chemical decomposition of DMSO stock solutions is a common
incident that can mislead biological screening campaigns. Here,
we share our case study of 2-aminothiazole 1, originating from
an antimalarial class that undergoes chemical decomposition in
DMSO at room temperature. As previously measured biological
activities observed against Plasmodium falciparum NF54 and for
the target enzyme PfIspE were not reproducible for a fresh
batch, we tackled the challenge to understand where the
activity originated from. Solvent- and temperature-dependent
studies using HRMS and NMR spectroscopy to monitor the
decomposition led to the isolation and in vitro evaluation of
several fractions against PfIspE. After four days of decomposition, we successfully isolated the oxygenated and dimerised
compounds using SFC purification and correlated the observed
activities to them. Due to the unstable nature of the two
isolates, it is likely that they undergo further decomposition
contributing to the overall instability of the compound
Operator Method for Nonperturbative Calculation of the Thermodynamic Values in Quantum Statistics. Diatomic Molecular Gas
Operator method and cumulant expansion are used for nonperturbative
calculation of the partition function and the free energy in quantum
statistics. It is shown for Boltzmann diatomic molecular gas with some model
intermolecular potentials that the zeroth order approximation of the proposed
method interpolates the thermodynamic values with rather good accuracy in the
entire range of both the Hamiltonian parameters and temperature. The systematic
procedure for calculation of the corrections to the zeroth order approximation
is also considered.Comment: 22 pages, 7 Postscript figures, accepted for publication in Journal
of Physics
Charge-density-wave instability in the Holstein model with quartic anharmonic phonons
The molecular-crystal model, that describes a one-dimensional electron gas
interacting with quartic anharmonic lattice vibrations, offers great potentials
in the mapping of a relatively wide range of low-dimensional fermion systems
coupled to optical phonons onto quantum liquids with retarded interactions.
Following a non-perturbative approach involving non-Gaussian partial functional
integrations of lattice degrees of freedom, the exact expression of the
phonon-mediated two-electron action for this model is derived. With the help of
Hubbard-Stratonovich transformation the charge-density-wave instability is
examined in the sequel, with particular emphasis on the effect of the quartic
anharmonic phonons on the charge-density-wave transition temperature.Comment: 12 pages, 3 figure
Characterizing RecA-Independent Induction of Shiga toxin2-Encoding Phages by EDTA Treatment
Background: The bacteriophage life cycle has an important role in Shiga toxin (Stx) expression. The induction of Shiga toxin-encoding phages (Stx phages) increases toxin production as a result of replication of the phage genome, and phage lysis of the host cell also provides a means of Stx toxin to exit the cell. Previous studies suggested that prophage induction might also occur in the absence of SOS response, independently of RecA. Methodology/Principal Findings: The influence of EDTA on RecA-independent Stx2 phage induction was assessed, in laboratory lysogens and in EHEC strains carrying Stx2 phages in their genome, by Real-Time PCR. RecA-independent mechanisms described for phage l induction (RcsA and DsrA) were not involved in Stx2 phage induction. In addition, mutations in the pathway for the stress response of the bacterial envelope to EDTA did not contribute to Stx2 phage induction. The effect of EDTA on Stx phage induction is due to its chelating properties, which was also confirmed by the use of citrate, another chelating agent. Our results indicate that EDTA affects Stx2 phage induction by disruption of the bacterial outer membrane due to chelation of Mg 2+. In all the conditions evaluated, the pH value had a decisive role in Stx2 phage induction. Conclusions/Significance: Chelating agents, such as EDTA and citrate, induce Stx phages, which raises concerns due to their frequent use in food and pharmaceutical products. This study contributes to our understanding of the phenomenon o
Non-covalent interactions of N-phenyl-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide derivatives—a case of intramolecular N-oxide hydrogen bonds
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